Impact thermostatic switch



1949- P. E. WILLMAN 2,433,685

IMPACT THERMOSTATIC SWITCH Filed May 13, 1947 2 Sheets-Sheet l INVENTOR.

PHILIP E. WILLMAN Oct. 4, 1949. P. E. WILLMAN IMPACT THERMOSTATIC SWITCH 2 Sheets-Sheet 2 Filed May 13, 1947 INVENTOR.

PHILIP E. WILLMAN Patented Oct. 4, 1949 IMPACT THERMOSTATIC SWITCH Philip E. Willman, Chicago, 111., assignor to Mc- Graw Electric Company, Elgin, 11L, 3 corporation of Delaware Application May 13, 1947, Serial No. 747,776

apparent from a description of several forms of device embodying my invention or will be set out in the course of such description and more particularly be set forth in the appended claims.

In the drawings,

Figure 1 is a top plan view of one form of device embodying my invention,

Fig. 2 is a vertical longitudinal section therethrough, taken on the line 22 of Fig. 1,

Fig. 3 is a view in vertical longitudinal section through another form of device embodying my invention,

Fig. 4 is a top plan view of still another form of device embodying my invention,

Fig. 5 is a vertical longitudinal section therethrough, taken on the line 5--5 of Fig. 4,

Fig. 6 is a vertical lateral section, taken on the line 6-6 of Fig. 5, and,

Fig. 7 is a view in vertical'lateral section, taken on the line 1-1 of Fig. 2.

Referring first of all to Figs. 1, 2 and 'l, I have there shown a snap-acting thermal switch designated generally by numeral comprising a metallic frame |3 of substantially hollow rectangular outline. The rectangular frame |3 comprises a lateral cross bar i5 at one end of the frame and a second cross bar |l extending across the other end of the frame l3. Cross bars l5 and I! are narrower than the longitudinal walls of the frame I3.

I provide a relatively small plate IQ of electrio-insulating material, which member I9 is secured against that end of frame l3 where member I! is also located, member l9 being secured against the upper surface of frame l3 by a plurality of screws 2| extending through member l9 and into member 3. I provide further a small frame member 23 which is secured against the upper surface of frame I3 by a plurality of screws 25. Member 23 is preferably made of brass and has an arcuate inner portion 21 for a purpose to be hereinafter set forth.

I provide a toggle comprising a first, relatively short, fixed arm 29 (which is member 23) and a second, relatively long, movable arm 3| together with a tension coil spring 33 connected to the two arms intermediate their ends. The arm 3| is pivotally mounted on the sharpened 2 end of arm 29 and has secured thereto at its right-hand end a small bar or plate .35 of electrio-insulating material, which plate is adapted to support an impact member 31 as well as a contact bridging member 39, both adjacent its lower surface. The contact bridging member 39 is adapted to be held in close engagement with two fixed contacts 4| and 43 secured against the upper surface of plate I9, more particularly by spring 33. A stop means 45 of substantially Z-shape is secured to the upper surface of plate Hand is provided with an adjustable stop 41 in the shape of a relatively small machine screw. I provide a second toggle comprising a first, relatively long, toggle arm 53 which is made of bimetal and which has pivotally secured thereto a second toggle arm 55, a spring 51 being connected to the two arms intermediate their respective ends. I provide further a stop or adjusting screw 59 in member whereby it is possible to adjust within certain limits the temperature at which snap-acting movement of the second arm will occur in an upward direction. I may secure the first toggle arm 53 against the upper surface of member l5 as by a plurality of screws 6|. An adjusting screw 60 having screwthreaded engagement with cross bar l5 permits of adjusting the temperature at which bimetal bar 53 will operate. The construction and adiustment of the parts of the switch is such that the normal position of all of the parts are substantially as shown in Fig. 2, that is, the contact bridging member 39 is normally in springpressed engagement with the contacts 4| and 43. The bimetal bar 53 will occupy substantially the position shown in Fig. 2 but will be moved in a clockwise direction upon, say, an increase of temperature until suddenly arm 55 will move upwardly into engagement with an adjusting means 63 in member 31 with an impact which will cause sudden disengagement of the contact bridging member 39 from the fixed contacts 4| and 63. The contact bridging member 39 will be held out of engagement with the fixed contacts 4| and 43 until the temperature to which particularly the bimetal arm 53 is subject has been reduced sufficiently to cause the bimetal arm 53 to move in a counter-clockwise direction with the result that at a certain temperature arm 53 and arm 55 will move backwardly into substantially the positions shown in Fig. 2 of the drawings. As is shown in Fig. 2, the tension center line of spring 33 passes below but close to the supporting pivot of arm 3|. When the switch has operated (by arm 55 striking screw 63 and lifting arm 3|) this center line lies even closer to the pivot but still lies below it to supply the downward force for closing the contacts when arm 55 snaps back to its normal position.

Referring now to Fig. 3 of the drawings, I have 3 there shown a modified form of device embodying my invention and comprising a hollow rectangular metal frame designated by numeral 55, having at its left-hand end a cross member 31 as well as a cross member 59 at its right-hand end. I provide a small bar or plate 'II of insulating material which may be secured as by screws (not -shown), which plate is adapted to have secured against its upper surface a pair of fixed contact members 13. A contact bridging member I5 is adapted 'to have engagement with the innermost surfaces of the pair of fixed contacts 13, contact bridging member 15 being secured to the under surface of a small block 11 of electricinsulating material, which block is secured to the free end of a leaf spring 19. Spring 19 has its fixed end secured as by a screw BI to a bar 83 of electric-insulation secured against the upper surface of the side walls of frame 65. A stop member 85 of substantially Z-shape is secured against the outer end of plate II and has a small machine screw 8'! extending therethrough, against which plate 'I'! may abut when the contact bridging member I5 has been moved out of engagement with fixed contact members 13. An impact member 89 secured to contact bridging member 15 extends through an opening 9| in plate II.

I provide a bimetal arm 93 secured as by one or more screws 95 against the upper surface of member 51. A second toggle arm 97 is pivotally mounted on the outer end of arm 93, the two arms being held by a tension coil spring 99, the coil spring being connected to the two arms 93 and 91 at points intermediate their respective ends. I provide means for adjusting the operating temperature comprising a manually adjustable screw IOI which has screw-threaded engagement with member 51. I provide an adjusting screw I05 in member 69 to fix the temperature differential of the snap-acting toggle arm comprising arms 93 and 91 and spring 99.

Referring now to Figs. 4 through 6, I have there shown a still further modification of a de'- vice embodying my invention and embodying a fiat longitudinally extending plate I01. Plate I01 has secured thereto at, say, its left-hand end, a member- I09 of substantially channel shape for supporting one arm I I I of bimetal, of a double arm toggle, in addition to a second arm II3 as well as a tension coil spring H5. The left-hand end ofarm I I I is secured to the upper portion of member I09 as by a plurality of rivets III. An adjusting screw H9 is also supported by the upper part of member I09 in order to permit of varying the operating temperature at which snap-acting movement of the arms III and H3 will occur from the positions shown in Fig. 5.

I provide a small block I2I of electric-insulating material which may be held against the .upper'surface of member I01 as by a plurality of rivets I23. Block I2I is provided with a plurality of fixed contact members I25 and I2! which may be held in proper operative position against the upper surface of plate I2I by suitable rivets I29 and I3I. Fixed contact members I25 and I27 are provided with screws I33 and I35 to 'permit of securing leads thereto. The fixed contact members I25 and I2! extend upwardly and then horizontally and have contact terminals I31 secured to their under surfaces.

I provide a movable contact bridging member I39 which is mounted on a pair of rods HI and I43 vertically movable in openings in member III. Contact bridging member I39 is held in close operative engagement with the fixed contact members I25 and I2! by springs I45 encircling the rods HI and I43. The springs will hold the contact bridging member in close operating engagement with the fixed contact members I25 and I2! until an impact member I41 secured to the outer end of the second arm II3 strikes the contact bridging member I39 upon snap-acting movement of arm II3 when a certain predetermined temperature is reached. I provide further an adjusting member I49 in a channel-shaped bracket I5I by means of which the temperature differential of operation of the double arm toggle comprising the bimetal arm III and the arm II3 may be adjusted.

It is evident that the various structures comprising my invention cause first of all a snapacting movement of the second arm of a toggle and that in two of the forms of device embodying my invention the impact member receives a sudden blow by one of the arms of the toggle after said arm has been set in motion. In the other form, namely, that shown in Fig. 5 of the drawings, the impact member receives a blow by a moving toggle arm and causes a contact bridging member to be disengaged from fixed contact members, this disengagement occurring only after the toggle arm has been set in motion, so that it will not strike the impact member until it has been caused to move at relatively high speed so that the interruption of the engagement between the fixed and the movable contacts will take place at relatively high speed. It is further evident that the pressure of engagement between the fixed and movable contacts is not decreased before the instant of entire and sudden disengagement of the two contacts.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof and I desire that all such modifications coming clearly within the scope of the appended claim shall be considered a part of my invention.

I claim as my invention:

A thermostatic switch comprising a pair of fixed contacts, a contact bridging member insulatedly mounted on one end of a toggle arm, a second fixed toggle arm, a tension spring connected to said toggle arms holding said bridging member in close engagement with said contacts,

operated, from moving over center.

PHILIP E. WILLMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,390,987 Denison Sept. 20, 1921 2,084,424 Bauman June 22, 1937 2,193,126 Furnas Mar. 12, 1940 2,374,967 Alexander May 1, 1945 

